# Copyright 2010 Matt Chaput. All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
#    1. Redistributions of source code must retain the above copyright notice,
#       this list of conditions and the following disclaimer.
#
#    2. Redistributions in binary form must reproduce the above copyright
#       notice, this list of conditions and the following disclaimer in the
#       documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY MATT CHAPUT ``AS IS'' AND ANY EXPRESS OR
# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
# EVENT SHALL MATT CHAPUT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
# OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
# EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
# The views and conclusions contained in the software and documentation are
# those of the authors and should not be interpreted as representing official
# policies, either expressed or implied, of Matt Chaput.

import sys
from whoosh.compat import xrange
from whoosh.matching import mcore


class WrappingMatcher(mcore.Matcher):
    """Base class for matchers that wrap sub-matchers.
    """

    def __init__(self, child, boost=1.0):
        self.child = child
        self.boost = boost

    def __repr__(self):
        return "%s(%r, boost=%s)" % (self.__class__.__name__, self.child,
                                     self.boost)

    def copy(self):
        kwargs = {}
        if hasattr(self, "boost"):
            kwargs["boost"] = self.boost
        return self.__class__(self.child.copy(), **kwargs)

    def depth(self):
        return 1 + self.child.depth()

    def _replacement(self, newchild):
        return self.__class__(newchild, boost=self.boost)

    def replace(self, minquality=0):
        # Replace the child matcher
        r = self.child.replace(minquality)
        if r is not self.child:
            # If the child changed, return a new wrapper on the new child
            return self._replacement(r)
        else:
            return self

    def max_quality(self):
        return self.child.max_quality()

    def id(self):
        return self.child.id()

    def all_ids(self):
        return self.child.all_ids()

    def is_active(self):
        return self.child.is_active()

    def reset(self):
        self.child.reset()

    def children(self):
        return [self.child]

    def supports(self, astype):
        return self.child.supports(astype)

    def value(self):
        return self.child.value()

    def value_as(self, astype):
        return self.child.value_as(astype)

    def spans(self):
        return self.child.spans()

    def skip_to(self, id):
        return self.child.skip_to(id)

    def next(self):
        self.child.next()

    def supports_block_quality(self):
        return self.child.supports_block_quality()

    def skip_to_quality(self, minquality):
        return self.child.skip_to_quality(minquality / self.boost)

    def block_quality(self):
        return self.child.block_quality() * self.boost

    def weight(self):
        return self.child.weight() * self.boost

    def score(self):
        return self.child.score() * self.boost


class MultiMatcher(mcore.Matcher):
    """Serializes the results of a list of sub-matchers.
    """

    def __init__(self, matchers, idoffsets, current=0):
        """
        :param matchers: a list of Matcher objects.
        :param idoffsets: a list of offsets corresponding to items in the
            ``matchers`` list.
        """

        self.matchers = matchers
        self.offsets = idoffsets
        self.current = current
        self._next_matcher()

    def __repr__(self):
        return "%s(%r, %r, current=%s)" % (self.__class__.__name__,
                                           self.matchers, self.offsets,
                                           self.current)

    def is_active(self):
        return self.current < len(self.matchers)

    def reset(self):
        for mr in self.matchers:
            mr.reset()
        self.current = 0

    def children(self):
        return [self.matchers[self.current]]

    def _next_matcher(self):
        matchers = self.matchers
        while (self.current < len(matchers)
               and not matchers[self.current].is_active()):
            self.current += 1

    def copy(self):
        return self.__class__([mr.copy() for mr in self.matchers],
                              self.offsets, current=self.current)

    def depth(self):
        if self.is_active():
            return 1 + max(mr.depth() for mr in self.matchers[self.current:])
        else:
            return 0

    def replace(self, minquality=0):
        m = self
        if minquality:
            # Skip sub-matchers that don't have a high enough max quality to
            # contribute
            while (m.is_active()
                   and m.matchers[m.current].max_quality() < minquality):
                m = self.__class__(self.matchers, self.offsets, m.current + 1)
                m._next_matcher()

        if not m.is_active():
            return mcore.NullMatcher()

        # TODO: Possible optimization: if the last matcher is current, replace
        # this with the last matcher, but wrap it with a matcher that adds the
        # offset. Have to check whether that's actually faster, though.
        return m

    def max_quality(self):
        return self.matchers[self.current].max_quality()

    def id(self):
        current = self.current
        return self.matchers[current].id() + self.offsets[current]

    def all_ids(self):
        offsets = self.offsets
        for i, mr in enumerate(self.matchers):
            for id in mr.all_ids():
                yield id + offsets[i]

    def spans(self):
        return self.matchers[self.current].spans()

    def supports(self, astype):
        return self.matchers[self.current].supports(astype)

    def value(self):
        return self.matchers[self.current].value()

    def value_as(self, astype):
        return self.matchers[self.current].value_as(astype)

    def next(self):
        if not self.is_active():
            raise mcore.ReadTooFar

        self.matchers[self.current].next()
        if not self.matchers[self.current].is_active():
            self._next_matcher()

    def skip_to(self, id):
        if not self.is_active():
            raise mcore.ReadTooFar
        if id <= self.id():
            return

        matchers = self.matchers
        offsets = self.offsets
        r = False

        while self.current < len(matchers) and id > self.id():
            mr = matchers[self.current]
            sr = mr.skip_to(id - offsets[self.current])
            r = sr or r
            if mr.is_active():
                break

            self._next_matcher()

        return r

    def supports_block_quality(self):
        return all(mr.supports_block_quality() for mr
                   in self.matchers[self.current:])

    def block_quality(self):
        return self.matchers[self.current].block_quality()

    def weight(self):
        return self.matchers[self.current].weight()

    def score(self):
        return self.matchers[self.current].score()


def ExcludeMatcher(child, excluded, boost=1.0):
    return FilterMatcher(child, excluded, exclude=True, boost=boost)


class FilterMatcher(WrappingMatcher):
    """Filters the postings from the wrapped based on whether the IDs are
    present in or absent from a set.
    """

    def __init__(self, child, ids, exclude=False, boost=1.0):
        """
        :param child: the child matcher.
        :param ids: a set of IDs to filter by.
        :param exclude: by default, only IDs from the wrapped matcher that are
            **in** the set are used. If this argument is True, only IDs from
            the wrapped matcher that are **not in** the set are used.
        """

        super(FilterMatcher, self).__init__(child)
        self._ids = ids
        self._exclude = exclude
        self.boost = boost
        self._find_next()

    def __repr__(self):
        return "%s(%r, %r, %r, boost=%s)" % (self.__class__.__name__,
                                             self.child, self._ids,
                                             self._exclude, self.boost)

    def reset(self):
        self.child.reset()
        self._find_next()

    def copy(self):
        return self.__class__(self.child.copy(), self._ids, self._exclude,
                              boost=self.boost)

    def _replacement(self, newchild):
        return self.__class__(newchild, self._ids, exclude=self._exclude,
                              boost=self.boost)

    def _find_next(self):
        child = self.child
        ids = self._ids
        r = False

        if self._exclude:
            while child.is_active() and child.id() in ids:
                r = child.next() or r
        else:
            while child.is_active() and child.id() not in ids:
                r = child.next() or r
        return r

    def next(self):
        self.child.next()
        self._find_next()

    def skip_to(self, id):
        self.child.skip_to(id)
        self._find_next()

    def all_ids(self):
        ids = self._ids
        if self._exclude:
            return (id for id in self.child.all_ids() if id not in ids)
        else:
            return (id for id in self.child.all_ids() if id in ids)

    def all_items(self):
        ids = self._ids
        if self._exclude:
            return (item for item in self.child.all_items()
                    if item[0] not in ids)
        else:
            return (item for item in self.child.all_items() if item[0] in ids)


class InverseMatcher(WrappingMatcher):
    """Synthetic matcher, generates postings that are NOT present in the
    wrapped matcher.
    """

    def __init__(self, child, limit, missing=None, weight=1.0, id=0):
        super(InverseMatcher, self).__init__(child)
        self.limit = limit
        self._weight = weight
        self.missing = missing or (lambda id: False)
        self._id = id
        self._find_next()

    def copy(self):
        return self.__class__(self.child.copy(), self.limit,
                              weight=self._weight, missing=self.missing,
                              id=self._id)

    def _replacement(self, newchild):
        return self.__class__(newchild, self.limit, missing=self.missing,
                              weight=self._weight, id=self._id)

    def is_active(self):
        return self._id < self.limit

    def reset(self):
        self.child.reset()
        self._id = 0
        self._find_next()

    def supports_block_quality(self):
        return False

    def _find_next(self):
        child = self.child
        missing = self.missing

        # If the current docnum isn't missing and the child matcher is
        # exhausted (so we don't have to worry about skipping its matches), we
        # don't have to do anything
        if not child.is_active() and not missing(self._id):
            return

        # Catch the child matcher up to where this matcher is
        if child.is_active() and child.id() < self._id:
            child.skip_to(self._id)

        # While self._id is missing or is in the child matcher, increase it
        while child.is_active() and self._id < self.limit:
            if missing(self._id):
                self._id += 1
                continue

            if self._id == child.id():
                self._id += 1
                child.next()
                continue

            break

    def id(self):
        return self._id

    def all_ids(self):
        return mcore.Matcher.all_ids(self)

    def next(self):
        if self._id >= self.limit:
            raise mcore.ReadTooFar
        self._id += 1
        self._find_next()

    def skip_to(self, id):
        if self._id >= self.limit:
            raise mcore.ReadTooFar
        if id < self._id:
            return
        self._id = id
        self._find_next()

    def weight(self):
        return self._weight

    def score(self):
        return self._weight


class RequireMatcher(WrappingMatcher):
    """Matches postings that are in both sub-matchers, but only uses scores
    from the first.
    """

    def __init__(self, a, b):
        from whoosh.matching.binary import IntersectionMatcher

        self.a = a
        self.b = b
        self.child = IntersectionMatcher(a, b)

    def copy(self):
        return self.__class__(self.a.copy(), self.b.copy())

    def supports_block_quality(self):
        return self.a.supports_block_quality()

    def replace(self, minquality=0):
        if not self.child.is_active():
            # If one of the sub-matchers is inactive, go inactive
            return mcore.NullMatcher()
        elif minquality and self.a.max_quality() < minquality:
            # If the required matcher doesn't have a high enough max quality
            # to possibly contribute, return an inactive matcher
            return mcore.NullMatcher()

        new_a = self.a.replace(minquality)
        new_b = self.b.replace()
        if not new_a.is_active():
            return mcore.NullMatcher()
        elif new_a is not self.a or new_b is not self.b:
            # If one of the sub-matchers changed, return a new Require
            return self.__class__(new_a, self.b)
        else:
            return self

    def max_quality(self):
        return self.a.max_quality()

    def block_quality(self):
        return self.a.block_quality()

    def skip_to_quality(self, minquality):
        skipped = self.a.skip_to_quality(minquality)
        self.child._find_next()
        return skipped

    def weight(self):
        return self.a.weight()

    def score(self):
        return self.a.score()

    def supports(self, astype):
        return self.a.supports(astype)

    def value(self):
        return self.a.value()

    def value_as(self, astype):
        return self.a.value_as(astype)


class ConstantScoreMatcher(WrappingMatcher):
    def __init__(self, child, score=1.0):
        super(ConstantScoreMatcher, self).__init__(child)
        self._score = score

    def copy(self):
        return self.__class__(self.child.copy(), score=self._score)

    def _replacement(self, newchild):
        return self.__class__(newchild, score=self._score)

    def block_quality(self):
        return self._score

    def score(self):
        return self._score





